Automatic piston for air-brakes



(No Model.) 2 Sheets-Sl1eet l.

N. J. PRITOHARD & J. S. TEMPLON.

AUTOMATIC PISTON FOR AIR BRAKES.

tented Mar. 5, 1889.

75 A0 DRUM I 755/34 E (YA/1705f (No Model.)

2 Sheets-Sheet 2.

N. J. PRITGHARD & J. S TEMPLON.

AUTOMATIG' PISTON PORAIR BRAKES.

Patented Mar. 5, 1889.

1% Mieooe o NR W 4 UNiTnD STATES PATENT @rricn NATHANIEL J'. PRITCHARD AND JAMES TEMPLO'N, Ol MILQ'ES, ASSIGXORS, BY DIRECT AND HESSE ASSIGNMENTS, TO THE PRITCHARD BRAKE COM- PANY, OF ROANOKE, VIRGINIA.

AUTOMATlC PlSTON FOR AIR=BRAKES.

SPECIFICATION forming part of Letters Patent No. 399,157, dated March 5, 1889. Application filed November 21, 1887. $eriai No. 255,790. (No model.)

To all whom it 11mg concern: The bottom of the cylindrical partA is closed Beitlcnown that we, NATHANIEL J .PRITOH- by means of a plate bolted thereto, which 50 ARD and JAMES S. TEMPLON, citizens of the carries a bulb-shaped air-chamber, 13. This United States, residing at l\[ilnes,in the county chamber receives at the bottom any drippings of Page and State of Virginia, have invented or other waste which may accumulate therecertain new and useful Improvements in Auin, whence they are removed by a draintomatic Pistons for Air-Brakes; and we do cock, 0. hereby declare the following to be afull, clear, The cylinder A is provided with ports and exact description of the invention, such where the several pipes are coupled that can as will enable others skilled in the art to which stitute the ordinary air-brake and lead to the it appertains to make and use the same. parts of the same,

This invention relates to an automatic air- Thus C denotes the port where coupling is piston for use in pneumatic railway-brakes made with the pipe which leads to the airfor the purpose of controlling the admission drum.

I 5 of air to the brake-cylinder; and it consists, D is the port where the pipe connected essentially, in the construction, arrangement, leading to the brake-cylinder. and combination of parts, substantially as E is a port located in the side wall of the will be hereinafter described, and then set bulb B, and at this point the pipe F enters, forth in the claims. which leads to the main air-supply pipe, and 20 In the annexed drawings, illustrating the through it air is introduced into the device. invention, Figure 1 is a vertical section of At port D connected a Tshaped pipe, as our improved automatic air piston for will be seen by reference to Figs. 2 and 5. 7o pneumatic railway-brakes, and shows the piss- This pipe has a horizontal portion running ton at the upper limit of its stroke. Fig. 2 is outward from the cylinder A, and at right 25 a horizontal section on the line cc of Fig. l. angles to this horizontal. portion is another Fig. 3 is a vertical section similar to that horizontal part, II. At the intersection of shown in Fig. 1, with the piston at the lower these two parts is located a plug-valve, G, 7 limit of its stroke. Fig. i is a detail elevawhich can be turned in the position shown in tion of the air-supplypipe and the pipe which Fig. 5, where air will pass through the pipe "0 leads to the brake-cylinder, together with H, communication being shut oit' from the other connections. Fig. 5 a sectional detail 1 port D; or said valve may be turned in the of certain of the pipes, and shows the arl position shown in Fig. "3, where air will pass rangement of the plug-valve when thedevice between the port D and the pipe I, which is to be used with straight air. leads to the hrake-cyliinler, and is coupled to 35 Similar letters of reference denote correone end of the pipe H.

sponding' parts throughout the several. fig- A short distance below the port.- D, in the ures. wall of the cylinder A, is located an exhaust- A represents a cylinder of any suitable diport, e. A vertical passage, 0, extends upniensions and made in any desired manner, ward through the wall of the cylinder A from 40 it being adapted to be arranged in an upthe bottom of said cylinder to the port C. right position beneath the car with which it Near the bottom of the cylinder communicais used. It may be made in one or more tion is established between the interior cham- 0 parts. In the drawings the preferable conher thereof and the passage 0 by a port, (1. struction is shown, consisting of the main cy- \Vithin the central chamber is located a 4 5 lindrical body, upon the top of which is a cappiston, 'Knvhich is preferably a doublepiston, plate, A, having an interiorly downward pro having" the lower head, Ti, and the upper head, jection,b, which limits the upward movement H. The head M flanged circumterentially of the piston within the cylindrical chamber. 1 at top and bottom, or otherwise suitably fash- .reference to Figs. 1 and 2.

ioned and shaped to permit an encircling ring, N, to be loosely arranged about the same, said ring being recessed for a portion of its circuinferential distance, as will be seen by The piston has a vertical movement up and down within the central chamber, and in said movement it comes into proper relation to the several ports and passages, hereinabove mentioned, to accomplish the results which will be farther on more specifically stated. hen the piston occupies its uppermost position, as seen in Fig. 1, air can easily pass from the brake-cylinder through pipe I into port D, and round past the recessed face of the encircling ring N into the exhaust-port c, where it will escape into the atmosphere. Vhen the piston is in its lowermost position, as shown in Fig. 3, will pass through port 0, over the airdrinn, into the interior chamber, and out through port D into the brake-cylinder,where it will set the brakes.

As already stated, pipe F connects with the main air-supply pipe and serves to introduce air into the air-chamber. Air thus introduced will pass upward in the direction shown by the arrows, Fig. 1, into the interior chamber of the cylinder, push'the piston upward until it passes beyond the port (I, and then go into the passage-way 0 up into the air-drum. It will also fill the space above the piston, so that said piston will be balanced.

Suppose now that it is desired to set the brakes. If straight air is to be used, all that need be done is to have the valve G located in the position shown in Fig. 5. Then the engineer by manipulating the valve upon the locomotive will cause air to rush through the supply-pipe until it reaches the pipe I-I, through which it will pass, as shown by the arrow, Fig. 5, onward into the pipe I, and thus to the brake-cylinder. lVhen automatic air is to be used, the plugG will be turned to occupy the position shown in Fig. 2. If it is desired to set the brakes automatically, the engineer will exhaust air by properly manipulating his valve, so that there will be less pressure beneath the piston than there is above it. This will cause the piston to tie scend until it reaches the position shown in Fig. 3, where it has passed down so loans to cease to cover the port D; hence air coming under pressure from the air-drum into the chamber above the piston will pass out through the port D and rush into the brakecylinder and set the brakes.

It will be noted that the encircling ring, which is loosely arranged about the head M of the piston, enables our device to be susceptible of great delicacy of 1novement,for,supposing the piston to be in the position shown in Fig. 1, the exhausting of a small amount of air from beneath it will cause it to drop enough to cover the port (Z. Afall of the piston far enough to enable the head L to cover the port CZ will not displace the ring N from its position, as it will be seen there is sufficient space between the ring N and the enoompassin flange of the head to permit this movement.

It has already been seen that the head M of the piston has an encircling ring loosely arranged about it, said ring being contained in an annular space in the piston-head. The vertical length of this packing-ring is shorter or less than the vertical length of the annular space within which it is contained, as Will be perceived upon an inspection of Fig. 1 or 3; hence it is evident that the piston may have a certain amount of vertical movement independent of any corresponding movement on the part of the packing-ring. The piston may move, therefore, to a certain extent without displacing the packing-ring from its position. The provision ofthis ring enables our device to be susceptible of great delicacy of movement, for, supposing the piston to be in the position shown in Fig. 1, it is evident that the exhausting of a very small amount of air from beneath. it will cause it to drop far enough to cover the port d. The piston in falling in this manner, however, will not displace the packing-ring, as the difference in vertical lengths between the packing-ring and the annular space within the piston-head is suffi cient to permit of enough movement on the part of the piston to close port (Z without interfering with the position of the packingring.

In Fig. 1. the parts are shown in the posi tion occupied when air is passing out of the bral e-cylinder through the exhaust, on the one hand, and air, on the other hand, is entering through the main pipe into the airchamber and up into the air-drum. The engineer by exhausting a very small portion of air from beneath the piston can close the port (Z .in the manner just stated, and yet will not interfere with the position of thepacking-ring which connects ports D and d. \Vhen the double-ended piston goes down farther, of course the ring N will be carried with it.

\Yhen the engineer desires to relieve the brakes, he will of course manipulate the valve upon the locomotive .so as to introduce air once more below the piston to cause the same to rise, so that communication may be had between the port D and the exhaust-port, when the air will readily pass from the brakecylinder into the atmosphere.

\Ve hereby disclaim the construction shown in the patent to Boyden, No. 280,285, June 26, 1883, and in the English Patent No. 3,000 of 1 S7 9.

Having thus described our invention,what we claim as new, and desire to secure by Letters Patent, is-

In a device for applying and relieving the air-pressure 011 railway-brakes, the combination of the inclosing-case A, whose top plate, A, has a downward projection, b, said case having port 0, leading to the air-drum, port D,leading' to the brake-cylinder, port E,Whe1'e ed to connect port D and exhaust-port 8, all the main pipe enters, the exhaust-port e in of said parts being arranged to operate subthe side Wall Of the cylinder nea-r pert D, the stantialiy in the manner and for the purpose vertical passage 0 and port d between it and described.

the interior chamber of the case, the T-shaped In testimony whereof We itffiK our signatures pipe connected to the casing at port D, and in presence of two Witnesses.

having a plug-valve, G,1ocated at the intersec- NATHANIEL J. PRITCHARD tion of its 1ne1nbers,t11e piston K within said i JAS. S. TEMPLON.

interior chamber of the casing, having heads L \Vitnesses:

and M, the loosely-placed ring N, surround- M. S. XVELFLEY,

ing head M, and having a recessed face adapt- E. T. BOOTON. 

